1. Field of the Invention
One embodiment of the present invention relates to a semiconductor device, a display panel, and an electronic device.
Note that one embodiment of the present invention is not limited to the above technical field. The technical field of the invention disclosed in this specification and the like relates to an object, a method, or a manufacturing method. Furthermore, one embodiment of the present invention relates to a process, a machine, manufacture, or a composition of matter.
In this specification and the like, a semiconductor device generally means a device that can function by utilizing semiconductor characteristics. A display device, a light-emitting device, an electro-optical device, a semiconductor circuit, and an electronic device include a semiconductor device in some cases.
2. Description of the Related Art
Various circuit configurations have been proposed for the pixels of active matrix display panels using light-emitting elements such as organic light emitting diodes (OLEDs). In general, a pixel is provided with at least a light-emitting element, a transistor which controls input of a data signal to the pixel, and a transistor which controls a current supplied to the light-emitting element (driving transistor). Supplying drain current flowing through the driving transistor to the light-emitting element enables the light-emitting element to emit light with a luminance corresponding to the value of the drain current. The drain current of the driving transistor is controlled by the voltage of a data signal.
Therefore, in the case where electrical characteristics (e.g., threshold voltage, field-effect mobility) of the driving transistor vary among a plurality of pixels that constitute a screen of a display panel, variations in luminance of the light-emitting element are generated even when data signals with the same voltage are supplied. Variations in electrical characteristics of the driving transistor among a plurality of pixels are one of the causes of reduction in display quality of a display panel.
For active matrix display panels, the number of pixels provided has been increased to achieve higher resolution, and hundreds of thousands to tens of millions of pixels are provided in one display panel. For example, if the resolution is full high definition (full-HD), the number of pixels is 1920×1080=2,073,600; if the resolution is 8K4K (Super Hi-Vision), the number of pixels is 7680×4320=33,177,600. It is very difficult for driving transistors of a large number of different pixels to have perfectly the same electrical characteristics. Thus, measuring the drain current of a driving transistor and compensating the luminance of a light-emitting element is proposed (e.g., Patent Document 1 and Non-Patent Document 1).